And it sounds not too far from the size of Randy's camper. He had a ton of posts and pictures and everything about how he built his. I think he called it the "stealth camper." Search around for those posts.
'03 Freightliner FL112, 295" wheel base, with '03 United Specialties 26' living quarters, single screw, Cat C12 430 h/p 1650 torque, Eaton 10speed , 3.42 rear axle ratio